Entergy's Waterford 3 nuclear plant on the west bank of St. Charles Parish is capable of withstanding an extreme natural disaster and is currently implementing additional safety measures to ensure against a Fukushima-type meltdown of its core reactors, according to a recent evaluation by the U.S. Nuclear Regulatory Commission. "What this means is that Entergy is on track to meet the requirements of this order that we issued last year in response to the Fukushima incident in Japan," NRC spokesman David McIntyre said. "It means that we approve of the plan and that they are taking steps to implement it."

While the NRC has said that all U.S. nuclear plants are constructed to withstand the most severe disasters expected for their locale, the agency required plants in 2012 to evaluate and upgrade equipment and safety plans to reduce the likelihood of damage from overheating and containment failure in the event of a complete loss of power. That's what happened in Japan in 2011, when three reactors at the Fukushima plant were morbidly damaged after an earthquake and tsunami in 2011 resulted in power failure.

The cleanup from that disaster continues amid concerns about radioactive air and water pollution.

Nuclear plants in the U.S., including Entergy's Waterford 3 plant located in Killona, were required to submit the upgraded safety plans to the Nuclear Regulatory Commission for evaluation. In a letter dated Nov. 22 to Waterford 3 officials, the NRC said it found "reasonable assurance" that Entergy's new plan "when properly implemented will meet the requirements" of the agency's order.

A major part of the order is the assurance that plant operators are able cool the nuclear reactor's core and prevent a meltdown in the face of a cataclysmic event. Responders at the Japan plant were unable to do that because its cooling capabilities were destroyed once water flooded its diesel generators, which were to serve as the back-up power supply.

McIntyre said the NRC's order was not based on safety deficiencies at U.S. plants but that Fukushima highlighted the very real possibility of extreme events. He described the mitigation strategies as answering "big what-ifs."

Fukushima "made the NRC and the industry rethink how we would deal with hypothetical scenarios that affect the plant's ability to shut down safely and preserve cooling capabilities for the reactor," he said. "The ultimate goals of these measures is to increase or preserve the capacity of the plant operators to safely shut down the plant. You can shut the plant down, but you also have to maintain the cooling."

Ron Perry, St. Charles Parish's emergency operations director and the former emergency planning coordinator at Waterford 3, said the plant's safety measures are extensive. "I think the chance of a meltdown prior to Fukushima was low," he said. "I'm assured that they are doing everything to withstand a similar situation."

He added: "We would never have heard of Fukushima if the diesel generators had not been overrun."

At Waterford 3, where Perry worked more than 30 years, disaster preparation takes into account the effect of unprecedented flooding and strong winds. The plant's generators are raised high off the ground in a concrete building with waterproof doors.

Even if the plant were to lose regular power, it would take the reactor coolant system, which is located in the concrete building, almost five days to reach a critical stage, according to the plansubmitted to the NRC.

"Fukushima prompted all nuclear sites within the industry, including Waterford 3, to carefully evaluate their equipment, practices and plans to ensure that they are appropriately robust," Waterford 3 spokesman Chris Winters said. "We are pleased that the recent NRC letter acknowledged Waterford 3's comprehensive strategies to mitigate risks from events similar to the conditions that resulted in the Fukushima incident."